Systems and methods for measurement of optical parameters in an optical network

ABSTRACT

A method includes determining a first power level by performing a first series of measurements based on a first series of burst transmissions from an optical transmitter of an optical network unit (ONU) in an optical network. Bursts in the first series of burst transmissions include a first modified preamble. A second power level is determined by performing a second series of measurements based on a second series of optical burst transmissions. Bursts in the second series of burst transmissions include a second modified preamble. A first power level (P 0 ) and a second power level (P 1 ) are determined based on the first power level and the second power level and one or more additional parameters associated with transmissions from the optical transmitter are determined based on P 0  and P 1 . Based on the additional parameters, it is determined whether the optical transmitter complies with specifications of the optical network.

RELATED APPLICATION

The patent application is a continuation of U.S. patent application Ser.No. 16/817,848 filed on Mar. 13, 2020, titled “SYSTEMS AND METHODS FORMEASUREMENT OF OPTICAL PARAMETERS IN AN OPTICAL NETWORK,” the disclosureof which is hereby incorporated by reference herein in its entirety.

BACKGROUND

A Passive Optical Network (PON) is an optical access network based on apoint-to-multipoint (P2MP) optical fiber topology, called an opticaldistribution network (ODN) that uses fiber and passive components, suchas splitters and combiners. A PON system uses the ODN to provideconnectivity between a plurality of central nodes and a plurality ofuser nodes using bi-directional wavelength channels. Parameters ofoptical transmitters in the central nodes and user nodes must bemeasured in order to verify compliance with specifications of the PONsystem and to ensure that a high quality of service is provided tocustomers.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 illustrates an exemplary environment in which systems and methodsdescribed herein may be implemented;

FIG. 2 illustrates exemplary components of a device that may be includedin one or more of the devices described herein;

FIG. 3 illustrates a burst transmission according to an implementation;

FIG. 4 illustrates an exemplary environment in which a power meter maybe used to determine parameters associated with a burst transmission;

FIG. 5 is a flow diagram illustrating a process for evaluating whether atransmitter meets the specifications of a passive optical network;

FIG. 6 illustrates an exemplary first burst using a modified firstpreamble; and

FIG. 7 illustrates an exemplary second burst using a modified secondpreamble.

DETAILED DESCRIPTION OF PREFERRED EMBODIMENTS

The following detailed description refers to the accompanying drawings.The same reference numbers in different drawings may identify the sameor similar elements.

An ODN may provide connectivity between a plurality of central nodes,known as optical line terminal network elements (OLTs), and plurality ofuser nodes, known as optical network units (ONUs) or optical networkterminals (ONTs), using a plurality of bi-directional wavelengthchannels that each include a downstream wavelength and an upstreamwavelength. In a conventional single-channel time-division multiplexed(TDM) PON system, each ONU may operate over a single fixed wavelengthchannel associated with a particular OLT channel termination (CT) over asingle ODN.

In a time and wavelength division multiplexed (TWDM) PON system, an ONUmay operate on a plurality of wavelength channels, one wavelengthchannel at a time. In a TWDM PON system, each wavelength channel may beassociated with its own OLT CT and a plurality of wavelength channelsmay be multiplexed over a single ODN. The OLT CTs that form the sameTWDM PON system may physically belong to the same module within a singleOLT network element, to different modules within a single OLT networkelement, or to different OLT network elements. The plurality of ONUs ina TWDM PON system operating on a particular wavelength channel at anygiven time may follow the conventional TDM PON system, using themechanisms of time-division multiplexing (TDM) in the direction from theOLT to the ONUs (the downstream transmission direction) andtime-division multiple access (TDMA) in the direction from the ONUtowards the OLT CT (the upstream transmission direction).

Each PON OLT CT and each PON ONU, which may collectively be referred toas PON network element (PON NEs), may contain an optical transmitterthat converts the electrical signal into optical form and launches orforwards the resulting modulated optical signal into the optical fiber.An optical transmitter may be characterized by a plurality of parametersthat define the ability of the transmitter to comply with aspecification of a particular PON system. The optical transmitterparameters may include, for example, operation mode, optical powerparameters, spectral parameters, temporal parameters, and otherparameters. For each individual PON NE, the parameters may have to beverified to confirm compliance with the PON system specification. Theparameter verification may be required in both laboratory and fieldenvironments.

Previously, measuring only the mean launch optical power (P_(mean)) ofan optical transmitter was necessary in order to determine whether theoptical transmitter was compliant with the specifications of aparticular PON system. More recently, however, it has become necessaryto take into account the extinction ratio of the optical transmitter inorder to achieve high performance specifications. Extinction ratio (ER)is a ratio of two optical power levels—that of the high intensity oflight, which usually corresponds to transmission of logical 1, denotedP₁, and that of the low intensity of light, which usually corresponds totransmission of logical 0, denoted P₀. As the overall requirements ofthe PON system increase, the optical transmitter specification maypresent a tradeoff between P_(mean) and ER. For example, an opticaltransmitter may have slightly lower mean optical power and slightlyhigher extinction ratio in order to meet the specifications of the PONsystem. Likewise, an optical transmitter may have slightly higher meanoptical power and slightly lower extinction ratio and meet the samespecifications.

By building the PON system specifications in a dependent way, it may bepossible to make more transmitters compliant and reduce the cost of theequipment. However, due to the complexities of the technology, it may bemore difficult to measure the additional parameters and to evaluate thecompliance of the transmitter with the specification of the PON system.For example, a technician in the field may easily be able to measure themean optical power of a transmitter using a compact handheld instrument.However, in order to measure the additional parameters (ER, opticalmodulation amplitude (OMA), etc.) that are specified in relation to eachother, the equipment that would normally be used may be prohibitivelylarge/bulky and expensive.

Systems and methods described herein provide for determining parameters,such as extinction ratio and/or optical modulation amplitude that may beused in conjunction with mean optical power to specify a complianttransceiver. The mean optical power may be measured in the field using acompact instrument. The optical power parameters and the additionalparameters are related by the following expressions:P _(mean)=(P ₀ +P ₁)/2;  (Equ. 1)OMA=P ₁ −P ₀;  (Equ. 2)ER=P ₁ /P ₀;  (Equ. 3)OMA=2 P _(mean)(ER−1)/(ER+1).  (Equ. 4)

The optical transmitter of a PON OLT may operate downstream in acontinuous wave operation mode (CW mode), launching an uninterruptedmodulated optical signal into the fiber. The optical transmitter of aPON ONU may operate in the burst mode (BM), remaining off or inactivemost of the time and only launching a modulated optical signal into thefiber when instructed to do so by the OLT CT. The optical powerparameters of the PON ONU optical transmitter may be specified andcontrolled only for the duration of an upstream transmission burst.

Direct application of Equations 1-4 above for calculation of extinctionratio ER and optical modulation amplitude OMA is only possible ifexpensive and bulky measurement equipment is used. System and methodsdescribed herein may allow the use of a compact instrument to obtainbiased measurements of average burst optical power with unbalancednumber of zeros and ones, having controlled measure of bias, tocalculate the approximate values of the power levels of P₀ and P₁, andto calculate the approximate values of extinction ratio ER and opticalmodulation amplitude OMA.

FIG. 1 is a block diagram illustrating an exemplary environment 100 inwhich systems and methods described herein may be implemented. As shownin FIG. 1 , environment 100 may include a plurality of OLT CTs 110-1 to110-N (also referred to as OLT CTs 110, or individually or generally asOLT CT 110) connected to a wavelength multiplexer (WM) 120 via channelattachment fibers 170-1 to 170-N (also referred to as channel attachmentfibers 170, or individually or generally as channel attachment fiber170), an ODN 130, and a plurality of ONUs 140-1 to 140-N (also referredto as ONU 140, or individually or generally as ONU 140). ODN 130 mayinclude a splitter 150 and a plurality of distribution fibers 160-1 to160-N (also referred to as distribution fibers 160, or individually orgenerally as distribution fiber 160) to connect splitter 150 and ONUs140.

OLT CTs 110 may correspond, for example, to optical blades or cardsassociated with optical signals carried via a PON, such as ODN 130, toONUs 140. For example, OLT CTs 110 may be located in a central office(not depicted) that provides a connection service to ODN 130 for ONUs140 located in customer premises (not depicted). The central office, forexample, may provide television channels, streaming content, and/orother type of content from a video content delivery system. OLT CTs 110may communicate with the customer premises via ODN 130 to provide dataand/or services to the customer premises. Functions of OLT CTs 110 maybe governed by one or more controllers (not depicted).

ONUs 140 may include devices to terminate distribution fibers 160 atcustomer premises. ONUs 140 may demultiplex incoming optical signalsinto component parts (such as voice telephone, television, andInternet), and provide the signals to user devices in customer premises.ONUs 140 may also transmit outgoing signals from devices in customerpremises.

Each of OLT CTs 110 may be associated with a separate wavelength orrange of wavelengths for sending downstream signals. Similarly, ONUs 140may be associated with separate wavelengths or ranges of wavelengths forsending upstream signals. An optical transmitter (not depicted) at OLTCT 110 may operate in a continuous wave mode and an optical transmitter(not depicted) at ONU 140 may operate in a burst mode.

The different downstream wavelengths associated with OLT CTs 110initially may be transmitted via channel attachment fibers 170 s to WM120. For example, as illustrated in FIG. 1 , one channel attachmentfiber 170-1 may carry a first wavelength channel and a separate channelattachment fiber 170-N may provide a different path for carrying asecond wavelength channel. Channel attachment fibers 170 may beconnected to WM 120, which may transmit the multiplexed wavelengthchannels into splitter 150. Splitter 150 may distribute the opticalsignal to ONUs 140 via distribution fibers 160.

Channel attachment fibers 170 and distribution fibers 160 may include,for example, fibers to transmit a corresponding wavelength andconnectors to couple to devices (e.g., OLT CTs 110, WM 120, splitter150, and ONUs 140). Channel attachment fibers 170 and distributionfibers 160 may include various other components not specificallydescribed herein.

Still referring to FIG. 1 , ODN 130 may include one or more additionalcomponents associated with a PON. For example, ODN 130 may includevarious passive optical components such as a filter, an attenuator, etc.

Although FIG. 1 illustrates exemplary components of environment 100, inother implementations, environment 100 may include fewer components,different components, differently arranged components, and/or additionalcomponents than those depicted in environment 100. Also, functionsdescribed as being performed by respective separate components ofenvironment 100 may be performed by a single component, or a singlefunction may be performed by multiple components of environment 100.

Furthermore, in FIG. 1 , the depicted particular arrangement and numberof components of environment 100 are illustrated for simplicity. Inpractice, there may be more or fewer OLT CTs 110, ONUs 140, and ODN 130than depicted in FIG. 1 . For example, there may be tens or evenhundreds of OLT CTs 110 associated with a single central office.

FIG. 2 is a diagram illustrating exemplary components of a device 200that may be included in one or more of the devices described herein. Forexample, some or all of the components of device 200 may be included inOLT CT 110 and ONU 140. As illustrated in FIG. 2 , device 200 includes abus 205, a processor 210, a memory/storage 215 that stores software 220and other data, a communication interface 225, an input 230, and anoutput 235. According to other embodiments, device 200 may include fewercomponents, additional components, different components, and/or adifferent arrangement of components than those illustrated in FIG. 2 anddescribed herein. Additionally, or alternatively, according to otherembodiments, multiple components may be combined into a singlecomponent. For example, processor 210, memory/storage 215, andcommunication interface 225 may be combined.

Bus 205 includes a path that permits communication among the componentsof device 200. For example, bus 205 may include a system bus, an addressbus, a data bus, and/or a control bus. Bus 205 may also include busdrivers, bus arbiters, bus interfaces, clocks, and so forth.

Processor 210 includes one or multiple processors, microprocessors, dataprocessors, co-processors, application specific integrated circuits(ASICs), controllers, programmable logic devices, chipsets,field-programmable gate arrays (FPGAs), application specificinstruction-set processors (ASIPs), system-on-chips (SoCs), centralprocessing units (CPUs) (e.g., one or multiple cores), microcontrollers,and/or some other type of component that interprets and/or executesinstructions and/or data. Processor 210 may be implemented as hardware(e.g., a microprocessor, etc.), a combination of hardware and software(e.g., a SoC, an ASIC, etc.), may include one or multiple memories(e.g., cache, etc.), etc.

Processor 210 may control the overall operation or a portion ofoperation(s) performed by device 200. Processor 210 may perform one ormultiple operations based on an operating system and/or variousapplications or computer programs (e.g., software 220). Processor 210may access instructions from memory/storage 215, from other componentsof device 200, and/or from a source external to device 200 (e.g., anetwork, another device, etc.). Processor 210 may perform an operationand/or a process based on various techniques including, for example,multithreading, parallel processing, pipelining, interleaving, etc.

Memory/storage 215 includes one or multiple memories and/or one ormultiple other types of storage mediums. For example, memory/storage 215may include one or multiple types of memories, such as random accessmemory (RAM), dynamic random access memory (DRAM), cache, read onlymemory (ROM), a programmable read only memory (PROM), a static randomaccess memory (SRAM), a single in-line memory module (SIMM), a dualin-line memory module (DIMM), a flash memory, and/or some other type ofmemory. Memory/storage 215 may include a hard disk (e.g., a magneticdisk, an optical disk, a magneto-optic disk, a solid state disk, etc.),a Micro-Electromechanical System (MEMS)-based storage medium, and/or ananotechnology-based storage medium. Memory/storage 215 may includedrives for reading from and writing to the storage medium.

Memory/storage 215 may be external to and/or removable from device 200,such as, for example, a Universal Serial Bus (USB) memory stick, adongle, a hard disk, mass storage, off-line storage, or some other typeof storing medium (e.g., a compact disk (CD), a digital versatile disk(DVD), a Blu-Ray disk (BD), etc.). Memory/storage 215 may store data,software, and/or instructions related to the operation of device 200.

Software 220 includes an application or a program that provides afunction and/or a process. Software 220 may also include firmware,middleware, microcode, hardware description language (HDL), and/or otherform of instruction. Software 220 may include an operating system.

Communication interface 225 permits device 200 to communicate with otherdevices, networks, systems, and/or the like. Communication interface 225includes one or multiple optical interfaces. Communication interface 225may include one or multiple wired and/or wireless interfaces.Communication interface 225 includes one or multiple transmitters andreceivers, or transceivers. Communication interface 225 may operateaccording to a protocol stack and a communication standard.Communication interface 225 may include one or multiple line cards. Forexample, communication interface 225 may include processor 210,memory/storage 215, and software 220.

Input 230 permits an input into device 200. For example, input 230 mayinclude a keyboard, a mouse, a display, a touchscreen, a touchlessscreen, a button, a switch, an input port, speech recognition logic,and/or some other type of visual, auditory, tactile, etc., inputcomponent. Output 235 permits an output from device 200. For example,output 235 may include a speaker, a display, a touchscreen, a touchlessscreen, a light, an output port, and/or some other type of visual,auditory, tactile, etc., output component.

Device 200 may perform a process and/or a function, as described herein,in response to processor 210 executing software 220 stored bymemory/storage 215. By way of example, instructions may be read intomemory/storage 215 from another memory/storage 215 (not shown) or readfrom another device (not shown) via communication interface 225. Theinstructions stored by memory/storage 215 cause processor 210 to performa process described herein. Alternatively, for example, according toother implementations, device 200 performs a process described hereinbased on the execution of hardware (processor 210, etc.).

FIG. 3 illustrates a burst that may be transmitted by ONU 140. Thetiming of an ONU burst may be controlled by the PON TDMA protocol. Anoptical transmitter of ONU 140 may normally be in an off or inactivestate with an emitted Tx Optical Power at or close to zero. When ONU 140transmits data, the timing of the transmission may be regulated by therising edge 370 of a rectangular-shaped Tx Enable signal. As shown inFIG. 3 , when the pulse of Tx Enable signal occurs, the opticaltransmitter may take a period of time, Enable Transient time 310, forthe level of Tx Optical Power to reach an operational state and transmitburst 320, comprising a modulated optical signal. After burst 320 istransmitted, falling edge 380 of the rectangular-shaped Tx Enable Signalmay cause the optical transmitter to stop transmitting burst 320 andreturn to the off or inactive state. As shown in FIG. 3 , when fallingedge 380 causes the optical transmitter to stop transmitting, Tx OpticalPower may take a period of time, Disable Transient time 330, to returnto zero (or close to zero).

The upstream transmission burst 320 may include a preamble 340, adelimiter 350, and a data section 360. Preamble 340 may allow a remoteend optical receiver to achieve clock and data signal amplituderecovery. Delimiter 350 may allow the remote end optical receiver todelineate the start of the data transmission. Data section 360 mayinclude a burst header and a burst payload.

When burst 320 occurs, a power meter may be applied to the burst modeoptical signal and used to detect the start and the end of burst 320. Apower meter may detect a plurality of bursts 320 over a period of timeand may average the measured optical power over a plurality of burstintervals 390 detected during the period of time. The discrepancybetween the average optical power of a BM optical signal measured by anoptical power meter and the formally defined P_(mean) gets smaller for asignal with a balanced number of zeros and ones and without longsequences of identical digits.

PON systems may provide the protocol-based facility for OLT CT 110 tocontrol burst preamble 340 in terms of preamble pattern, preamblepattern length, and preamble pattern repeat count. Typically, thefacility may be able to optimize the optical signal reception given aspecific type and model of the OLT CT 110 and ONU 140 optical modules.In one embodiment, the facility may systematically create burstpreambles 340 with an unbalanced number of zeros. In this way, biasedmeasurements of average burst optical power may be obtained with acontrolled measure of bias to calculate the approximate values of thepower levels of P₀ and P₁ and to calculate the approximate values of ERand OMA using the expressions described above.

FIG. 4 is a diagram illustrating an exemplary environment 400 in whichmeasurements may be taken to determine whether an optical transmitter iscompliant with the specifications of a PON. Environment 400 may includeOLT CT 110, ODN 130, ONU 140, distribution fiber 160, PON power meter410, and communications channel 420.

As shown in FIG. 4 , in order to perform measurements of the opticalparameters of ONU 140, PON power meter 410 may be attached between ODN130 and ONU 140 via distribution fiber 160. PON power meter 410 may beconfigured to receive and measure the optical power in a series of burstsignals from ONU 140. For example, using a controlled burst preamble,PON power meter 410 may determine the average burst optical power of theseries of burst signals and calculate the approximate values ofadditional parameters (P₀, P₁, ER, and/or OMA) associated with thebursts to determine the compliance of an optical transmitter associatedwith ONU 140 with specifications of the PON.

As shown in FIG. 4 , communications channel 420 may be establishedbetween OLT CT 110 and PON power meter 410. In one embodiment,communications channel 420 may be established by setting up anout-of-band communications channel between a field technician at thesame location as PON power meter 410 and an operator at a central officeassociated with OLT CT 110. For example, communications channel 420 maybe established by establishing a cellular network phone call between thefield technician at power meter 410 and the operator at OLT CT 110. Inanother implementation, communications channel 420 may comprise anautomated out-of-band signaling channel, an in-band signaling channelvia an activated ONU 140, or a different type of signaling channel.

Using communications channel 420, OLT CT 110 may negotiate a duration ofa series of bursts during which a series of power measurements may betaken by PON power meter 410. In addition, using communications channel420, OLT CT 110 may instruct ONU 140 to use a specified modifiedpreamble and maintain the specified modified preamble during theduration of the series of measurement bursts. As described below in FIG.5 , based on the modified preamble, PON power meter 410 may obtainoptical power measurements associated with ONU 140 and, based on theoptical power measurements, may calculate the approximate values of theadditional parameters associated with the burst transmission todetermine a compliance of an optical transmitter associated with ONU 140with specifications of the PON.

FIG. 5 is a flow diagram illustrating a process 500 for evaluatingwhether a transmitter meets the specifications of a passive opticalnetwork. Process 500 may be performed using PON power meter 410.

Process 500 may begin by determining a first duration and a firstmodified preamble for performing a first series of optical powermeasurements (block 510). For example, a duration of a first measurementseries may be negotiated between PON power meter 410 and OLT CT 110 overcommunications channel 420. In one implementation, the duration mayindicate a number of bursts over which to perform optical powermeasurements. In another implementation, the duration may indicate aperiod of time over which to perform the optical power measurements. Inaddition, OLT CT 110 may instruct ONU 140 to use the first modifiedpreamble and to maintain the first modified preamble for the entireduration of the first series of optical power measurement.

Process 500 may continue by using the first modified preamble to performthe first series of optical power measurements (block 520). In oneimplementation, an optical transmitter associated with ONU 140 maytransmit a first series of bursts using the first modified preamble andPON power meter 410 may perform a series of optical power measurementsover the specified duration. For example, PON power meter 410 may detecta series of bursts over the negotiated duration and may average themeasured optical power over the burst intervals 390 detected during theduration to produce a first optical power level reading. Continuing withFIG. 5 , once the first series of optical power measurements using thefirst modified preamble has been completed, the first optical powerlevel reading may be stored (block 530).

Process 500 may continue by determining a second duration and a secondmodified preamble for performing a second series of optical powermeasurements (block 540). The second duration and the second modifiedpreamble may be determined in a manner similar to the manner in whichthe first duration and the first modified preamble were determined. Thesecond modified preamble may be used to perform the second series ofoptical power measurements over the second duration (block 550). Thesecond series of optical power measurements may produce a second opticalpower level reading.

Process 500 may continue by performing calculations to determine theapproximate values of P₀ and P₁ (block 560). For example, the firstoptical power level reading may be retrieved and used in conjunctionwith the second optical power level reading to solve a linear system ofequations to obtain approximate values of power level P₀ and power levelP₁. Examples of the linear systems of equations used to obtainapproximate values of P₀ and P₁ are described below with respect toFIGS. 6 and 7 .

When P₀ and P₁ have been determined, process 500 may continue bycalculating additional parameters associated with the opticaltransmitter (block 570). In one implementation the optical modulationamplitude (OMA) and the extinction ratio (ER) for the transmitter may becalculated. For example, the optical modulation amplitude may becalculated using the expression OMA=P₀−P₁ and the extinction ratio maybe calculated using the expression ER=P₁/P₀.

Using the power levels, optical modulation amplitude, and/or theextinction ratio, it may be determined whether the transmitter meets thespecifications of the passive optical network (block 580). In oneimplementation, the mean launch optical power and optical extinctionratio values that meet the specifications for the optical transmittermay form an envelope curve. Therefore, using PON power meter 410, atechnician in the field may be able to validate the compliant level ofthe upstream mean launch optical power corresponding to the validatedextinction ratio operating point on the envelope curve

FIG. 6 illustrates an exemplary structure of a first upstreamtransmission burst 600 transmitted by a transmitter associated with ONU140 using a first modified preamble. FIG. 7 illustrates an exemplarystructure of a second upstream transmission burst 700 transmitted by thetransmitter associated with ONU 140 using a second modified preamble. Asshown in FIG. 6 , first upstream transmission burst 600 may comprise afirst modified preamble 610, a delimiter 620, a framing sublayer (FS)burst 630, and a first preamble pattern 640. As shown in FIG. 7 , secondupstream transmission burst 700 may include a second modified preamble710, a delimiter 720, FS burst 730, and second preamble pattern 740.

A preamble of a regular burst typically may be balanced in terms ofzeros and ones and comprise a high density of transitions. In contrast,first modified preamble 610 and second modified preamble 710 may bebiased towards a single type of binary digit and may comprise thelongest possible preamble pattern that ensures controlled runs ofconsecutive identical digits and a largest possible repeat count.

As shown in FIG. 6 , first modified preamble 610 may use first preamblepattern 640, which is numerically equal to 0xA000 0000 0000 0000 and iscomposed of a first section of alternating zeros and ones and a secondsection of all zeros. The first preamble pattern is 8 octets long (themaximum preamble pattern length allowed under ITU-T Rec G.989.3), isheavily biased towards zeros, and is repeated 255 times (the maximumpreamble pattern repeat count under ITU-T Rec G.989.3). As shown in FIG.7 , second modified preamble 710 may use second preamble pattern 740,which is numerically equal to 0xAFFF FFFF FFFF FFFF and is composed of afirst section of alternating zeros and ones and a second section of allones. The second preamble pattern is 8 octets long, is heavily biasedtowards ones, and is repeated 255 times.

Delimiters 620 and 720 may be chosen to use a standard recommendedpattern to facilitate the OLT CT burst delineation. The standarddelimiter pattern is 4 octets long and is balanced in terms of zeros andones. FS bursts 630 and 730 may be of minimum possible size, comprisingan FS header (4 octets), the minimum allocation of 4 octets (upstreambuffer report), and an FS trailer (4 octets). Because FS bursts 630 and730 may be scrambled before transmission, FS bursts 630 and 730 may beconsidered balanced in terms of zeros and ones.

The total lengths of burst 600 and burst 700 may be 8*255+16=2056octets. Burst 600 may comprise 7*255=1785 all-zeros octets and255+16=271 balanced octets. Burst 700 may comprise 7*255=1785 all-onesoctets and 255+16=271 balanced octets.

If L1 denotes the power level reading obtained as a result of performinga first series of optical power measurements using first modifiedpreamble 610, and L2 denotes the power level reading obtained as aresult of performing a second series of optical power measurements usingsecond modified preamble 710, then the power level reading may beexpressed in terms of the power level P₀ and the power level P₁ asfollows:L1=1785/2056*P ₀+271/2056*P _(mean);L2=1785/2056*P ₁+271/2056*P _(mean).

From there, an approximate value of the OMA and ER may be obtained,respectively as:OMA=P ₁ −P ₀=2056/1785(L2−L1);ER=P ₁ /P ₀=(1920.5L2−135.5L1)/(1920.5L1−135.5L2).

Based on the calculations of OMA and/or ER, an operator may determinewhether the optical transmitter meets the specifications required by thePON.

In the preceding specification, various preferred embodiments have beendescribed with reference to the accompanying drawings. It will, however,be evident that various modifications and changes may be made thereto,and additional embodiments may be implemented, without departing fromthe broader scope of the invention as set forth in the claims thatfollow. The specification and drawings are accordingly to be regarded inan illustrative rather than restrictive sense.

For example, while a series of blocks have been described with respectto FIG. 5 , and a series of signals with respect to FIGS. 6 and 7 , theorder of the blocks and/or signals may be modified in otherimplementations. Further, non-dependent blocks may be performed inparallel.

It will be apparent that systems and/or methods, as described above, maybe implemented in many different forms of software, firmware, andhardware in the implementations illustrated in the figures. The actualsoftware code or specialized control hardware used to implement thesesystems and methods is not limiting of the embodiments. Thus, theoperation and behavior of the systems and methods were described withoutreference to the specific software code—it being understood thatsoftware and control hardware can be designed to implement the systemsand methods based on the description herein.

Further, certain portions, described above, may be implemented as acomponent that performs one or more functions. A component, as usedherein, may include hardware, such as a processor, an ASIC, or a FPGA,or a combination of hardware and software (e.g., a processor executingsoftware).

It should be emphasized that the terms “comprises”/“comprising” whenused in this specification are taken to specify the presence of statedfeatures, integers, steps or components but does not preclude thepresence or addition of one or more other features, integers, steps,components or groups thereof.

The term “logic,” as used herein, may refer to a combination of one ormore processors configured to execute instructions stored in one or morememory devices, may refer to hardwired circuitry, and/or may refer to acombination thereof. Furthermore, a logic may be included in a singledevice or may be distributed across multiple, and possibly remote,devices.

For the purposes of describing and defining the present invention, it isadditionally noted that the term “substantially” is utilized herein torepresent the inherent degree of uncertainty that may be attributed toany quantitative comparison, value, measurement, or otherrepresentation. The term “substantially” is also utilized herein torepresent the degree by which a quantitative representation may varyfrom a stated reference without resulting in a change in the basicfunction of the subject matter at issue.

To the extent the aforementioned embodiments collect, store, or employpersonal information of individuals, it should be understood that suchinformation shall be collected, stored, and used in accordance with allapplicable laws concerning protection of personal information.Additionally, the collection, storage and use of such information may besubject to consent of the individual to such activity, for example,through well known “opt-in” or “opt-out” processes as may be appropriatefor the situation and type of information. Storage and use of personalinformation may be in an appropriately secure manner reflective of thetype of information, for example, through various encryption andanonymization techniques for particularly sensitive information.

No element, act, or instruction used in the present application shouldbe construed as critical or essential to the embodiments unlessexplicitly described as such. Also, as used herein, the article “a” isintended to include one or more items. Further, the phrase “based on” isintended to mean “based, at least in part, on” unless explicitly statedotherwise.

What is claimed is:
 1. A method comprising: configuring a first burst preamble including a first repeating preamble pattern that is biased with respect to a first data bit value over a second data bit value, wherein the first repeating preamble pattern includes a first data signal that is balanced with respect to the first data bit value and the second data bit value; performing a first series of measurements based on a first series of burst transmissions from an optical transmitter of an optical network unit (ONU) in an optical network, wherein first bursts in the first series of burst transmissions include the first burst preamble; determining a first optical power level based on the first series of measurements; configuring a second burst preamble including a second repeating preamble pattern that is biased with respect to the second data bit value over the first data bit value, wherein the second repeating preamble pattern includes a second data signal that is balanced with respect to the first data bit value and the second data bit value; performing a second series of measurements based on a second series of burst transmissions from the optical transmitter, wherein second bursts in the second series of burst transmissions include the second burst preamble; and determining a second optical power level based on the second series of measurements.
 2. The method of claim 1, wherein the first repeating preamble pattern further comprises: a third data signal that contains all logical zeros; and wherein the second repeating preamble pattern further comprises: a fourth data signal that contains all logical ones.
 3. The method of claim 1, wherein configuring the first burst preamble comprises controlling the first repeating preamble pattern with respect to a first data bit pattern, a first length, and a first repeat count, and wherein configuring the second burst preamble comprises controlling the second repeating preamble pattern with respect to a second data bit pattern, a second length, and a second repeat count.
 4. The method of claim 3, wherein the first data bit pattern and the second data bit pattern correspond to a first section of alternating data bit values, and a second section of identical data bit values, wherein the first length and the second length correspond to 8 octets, and wherein the first repeat count and the second repeat count correspond to
 255. 5. The method of claim 1, further comprising: transmitting the first bursts upon a first transmission optical power level reaching a first operational state, and transmitting the second bursts upon a second transmission optical power level reaching a second operational state.
 6. The method of claim 1, further comprising: calculating, based on a mathematical relationship between the first optical power level and the second optical power level, an extinction ratio (ER) for the optical transmitter; and validating, based on the first optical power level, the second optical power level, and the ER, a compliance level associated with the optical transmitter with respect to specifications of the optical network.
 7. The method of claim 1, further comprising: calculating, based on a mathematical relationship between the first optical power level and the second optical power level, an optical modulation amplitude (OMA) for the optical transmitter; and validating, based on the first optical power level, the second optical power level, and the OMA, a compliance level associated with the optical transmitter with respect to specifications of the optical network.
 8. A system comprising: an optical network unit (ONU) including an optical transmitter; and a power meter configured to connect to the ONU, wherein the power meter is further configured to: configure a first burst preamble including a first repeating preamble pattern that is biased with respect to a first data bit value over a second data bit value, wherein the first repeating preamble pattern includes a first data signal that is balanced with respect to the first data bit value and the second data bit value; perform a first series of measurements based on a first series of burst transmissions from the optical transmitter of the ONU in an optical network, wherein first bursts in the first series of burst transmissions include the first burst preamble; determine a first optical power level based on the first series of measurements; configure a second burst preamble including a second repeating preamble pattern that is biased with respect to the second data bit value over the first data bit value, wherein the second repeating preamble pattern includes a second data signal that is balanced with respect to the first data bit value and the second data bit value; perform a second series of measurements based on a second series of burst transmissions from the optical transmitter, wherein second bursts in the second series of burst transmissions include the second burst preamble; and determine a second optical power level based on the second series of measurements.
 9. The system of claim 8, wherein the first repeating preamble pattern further comprises: a third data signal that contains all logical zeros; and wherein the second repeating preamble pattern further comprises: a fourth data signal that contains all logical ones.
 10. The system of claim 8, wherein, when configuring the first burst preamble, the power meter is configured to: control the first repeating preamble pattern with respect to a first data bit pattern, a first length, and a first repeat count, and wherein, when configuring the second burst preamble, the power meter is configured to: control the second repeating preamble pattern with respect to a second data bit pattern, a second length, and a second repeat count.
 11. The system of claim 10, wherein the first data bit pattern and the second data bit pattern correspond to a first section of alternating data bit values, and a second section of identical data bit values, wherein the first length and the second length correspond to 8 octets, and wherein the first repeat count and the second repeat count correspond to
 255. 12. The system of claim 8, wherein the power meter is further configured to: transmit the first bursts upon a first transmission optical power level reaching a first operational state, and transmit the second bursts upon a second transmission optical power level reaching a second operational state.
 13. The system of claim 8, wherein the power meter is configured to: calculate, based on a mathematical relationship between the first optical power level and the second optical power level, an extinction ratio (ER) for the optical transmitter; and validate, based on the first optical power level, the second optical power level, and the ER, a compliance level associated with the optical transmitter with respect to specifications of the optical network.
 14. The system of claim 8, wherein the power meter is further configured to: calculate, based on a mathematical relationship between the first optical power level and the second optical power level, an optical modulation amplitude (OMA) for the optical transmitter; and validate, based on the first optical power level, the second optical power level, and the OMA, a compliance level associated with the optical transmitter with respect to specifications of the optical network.
 15. A non-transitory computer readable medium comprising instructions, the instructions comprising: one or more instructions that, when executed by a processor of a power meter configured to connect to an optical network unit (ONU), cause the power meter to: configure a first burst preamble including a first repeating preamble pattern that is biased with respect to a first data bit value over a second data bit value, wherein the first repeating preamble pattern includes a first data signal that is balanced with respect to the first data bit value and the second data bit value; perform a first series of measurements based on a first series of burst transmissions from an optical transmitter of the ONU in an optical network, wherein first bursts in the first series of burst transmissions include the first burst preamble; determine a first optical power level based on the first series of measurements; configure a second burst preamble including a second repeating preamble pattern that is biased with respect to the second data bit value over the first data bit value, wherein the second repeating preamble pattern includes a second data signal that is balanced with respect to the first data bit values and the second data bit values; perform a second series of measurements based on a second series of burst transmissions from the optical transmitter, wherein second bursts in the second series of burst transmissions include the second burst preamble; and determine a second optical power level based on the second series of measurements.
 16. The non-transitory computer readable medium of claim 15, wherein the first repeating preamble pattern further comprises: a third data signal that contains all logical zeros; and wherein the second repeating preamble pattern further comprises: a fourth data signal that contains all logical ones.
 17. The non-transitory computer readable medium of claim 15, wherein the one or more instructions that cause the power meter to configure the first burst preamble include one or more instructions that cause the power meter to: control the first repeating preamble pattern with respect to a first data bit pattern, a first length, and a first repeat count, and wherein the one or more instructions that cause the power meter to configure the second burst preamble include one or more instructions that cause the power meter to: control the second repeating preamble pattern with respect to a second data bit pattern, a second length, and a second repeat count.
 18. The non-transitory computer-readable medium of claim 17, wherein the first data bit pattern and the second data bit pattern correspond to a first section of alternating data bit values, and a second section of identical data bit values, wherein the first length and the second length correspond to 8 octets, and wherein the first repeat count and the second repeat count correspond to
 255. 19. The non-transitory computer readable medium of claim 15, wherein the one or more instructions further cause the power meter to: calculate, based on a mathematical relationship between the first optical power level and the second optical power level, an extinction ratio (ER) for the optical transmitter; and validate, based on the first optical power level, the second optical power level, and the ER, a compliance level associated with the optical transmitter with respect to specifications of the optical network.
 20. The non-transitory computer readable medium of claim 15, wherein the one or more instructions further cause the power meter to: calculate, based on a mathematical relationship between the first optical power level and the second optical power level, an optical modulation amplitude (OMA) for the optical transmitter; and validate, based on the first optical power level, the second optical power level, and the OMA, a compliance level associated with the optical transmitter with respect to specifications of the optical network. 